Diagnosis Of Filamentary Dielectric Barrier Discharge By Using Molecular Beam Mass Spectrometry And Optical Emission Spectrometry In N₂

Molecular-beam mass spectrometry(MBMS)and optical emission spectroscopy(OES) techniques have been used respectively to diagnose the N⁺ and N₂⁺ in nitrogen plasmas produced by filamentary dielectric barrier discharges(DBD)and measured molecular temporal-vibrational temperature at atmospheric pressure.The main results presented in the dissertation have been summarized as follows:1.Active species produced by pure nitrogen filamentary dielectric barrier discharges have been diagnosed by the molecular beam mass spectrometry(MBMS)at gas pressure from 50 to 220 Torr.Under our experimental conditions,it is found that the main ion species are N₂⁺ and N⁺,and the concentration of I(N⁺)/I(N₂⁺)keep a stable value with changing discharge voltage and frequency.It is the first time for diagnosis of nitrogen plasma in high pressure by MBMS,the nitrogen ion signals rise with increasing discharge voltage and frequency,but exhibit a clear peak over the N₂ pressure range studied.The kinetics of the physicochemical processes involved in the earlier N₂ plasma has been studied.2.Temporal emission spectral lines of the N₂ second positive band system(C³Î _u→B³Î _g) in filamentary dielectric barrier discharge(DBD)at atmospheric pressure,in which the needle-plate was employed,was measured for the first time by using a method of spectrum diagnosis.Calculated the temporal vibrational temperature of N₂(C³Î _u→B³Î _g)molecules at different pressure and voltage.The experiment results show that the molecular vibrational temperature of N₂ is in the range from 2000 K to 3500 K,and it reduces with increasing time in a discharge cycle.The vibrational temperature rises with increasing discharge voltage and reduces with increasing pressure.